JP2512579B2 - Bulk paper manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used as a surface material for sanitary products and sanitary materials, a liquid absorbent material, an interlining material, a base cloth or a packaging material, and has sublimation, flexibility and other properties. To provide a paper excellent in uniformity and elasticity and a method for producing the paper at low cost by a highly productive papermaking method.

(Prior Art) Conventionally, to obtain a sublime paper by a wet papermaking method using a fiber having a latent crimp property is disclosed in, for example, JP-A-54-2479, JP-A-59-36800, and Synthetic Paper Research Institute. Social magazine No.13, 4th
Proposed on pages 7-52 (1974). On the other hand, the dispersibility of fibers during wet papermaking causes a decrease in the strength of the finally obtained paper, density unevenness, etc., so uniform dispersion is necessary, and therefore crimping is required during papermaking. Straight fibers that have not been used have been used.

(Problems to be Solved by the Invention) As described above, composite fibers having latent crimping performance are often used in order to obtain sublime paper, but such composite fibers are left in a ring shape with standing for several days. A morphological change occurs, and even if such a fiber is used, the dispersibility in water is poor and it is difficult to produce a good quality paper.

The object of the present invention is to solve the above problems, polyester having excellent dispersibility at the time of papermaking even when using a composite fiber having a latent crimping ability, and having excellent sublimability, flexibility and mechanical properties. It is intended to provide a method for producing sublime paper.

(Means for Solving the Problems) The inventors of the present invention have made extensive studies as a result of achieving the above object, and as a result, as a raw material fiber, a specific number of composite fibers having a specific dry heat shrinkage ratio and a latent crimping capacity have been obtained. By applying the mechanical crimp of, and using the one cut to a specific length,
Surprisingly, the inventors have found that the dispersibility of fibers during papermaking becomes extremely uniform, and that the finally obtained paper exhibits excellent sublimation, flexibility, and mechanical properties, and arrived at the present invention.

That is, the present invention has a free shrinkage ratio of 20% or less in a dry heat treatment at 170 ° C., and the number of crimps after the dry heat treatment is 40 pieces / 25 mm.
It has latent crimping ability to develop the above three-dimensional crimps,
30% by weight or more of an eccentric core-sheath type or side-by-side type polyester composite fiber (hereinafter sometimes referred to as latent crimpable polyester composite fiber) having a mechanical crimp of 25 mm and a fiber length of 3 to 30 mm Binder fibers that are heat-sealed at 200 ° C or less (hereinafter referred to as heat-bonding binder fibers)
The method for producing sublime paper is characterized in that the wet paper is made from an aqueous dispersion of a fiber mixture containing 5% by weight or more and heat-treated at 130 to 180 ° C.

In the present invention, the above-mentioned object cannot be achieved unless all the above-mentioned constitutional requirements are satisfied, but the most important point in the point of uniform dispersion is a fiber to which a mechanical crimp is applied at the time of papermaking. This is a surprising finding from the idea that it cannot be uniformly dispersed unless straight fibers are used, as in the prior art.

The eccentric core-sheath type or side-by-side type polyester composite fiber used in the present invention has a free shrinkage rate of 20% or less in a dry heat treatment at 170 ° C., and a three-dimensional number of crimps of 40 pieces / 25 mm or more after the heat treatment. There is no particular limitation as long as it has a latent crimping ability to develop crimps,
To be more specific, what is preferably used is basically composed of two kinds of polymers having different shrinkages. For example, the polymer component (A) on the high shrinkage side is preferably the main component of repetition. 1 to 6 mol% of isophthalic acid whose constituent unit is ethylene terephthalate and has a metal sulfonate group as a copolymer component, and 0 to 10 mol% of isophthalic acid, preferably 4 to 8 mol% Modified polyesters can be used. Even if isophthalic acid is not copolymerized, the polymerization reaction of polyester can appropriately proceed to produce a polyester composite fiber having a latent crimping ability within the scope of the present invention, but in order to further enhance the sublimeness of paper. Is preferably copolymerized with isophthalic acid. On the other hand, when the isophthalic acid content exceeds 10 mol%, it becomes difficult to stably obtain an appropriate degree of polymerization, and the crimp fastness is remarkably reduced. Further, isophthalic acid having a metal sulfonate group to be copolymerized is used to keep the melt viscosity at an appropriate level and to make latent crimp development capability manifest within the scope of the present invention. As the isophthalic acid having a metal sulfonate group, 5-sodium sulfoisophthalic acid,
Examples include 5-potassium sulfoisophthalic acid and 5-lithium sulfoisophthalic acid. When polymerizing polyethylene terephthalate with an ester-forming compound having a metal sulfonate group such as an ester-forming derivative, 1
The polymer (A) can be obtained by adding it in the range of ˜6 mol%, and optionally adding the above isophthalic acid for copolymerization. In addition to this, a polyethylene terephthalate polymer in which a high proportion of isophthalic acid having a metal sulfonate group is copolymerized is prepared in advance, and a polyethylene terephthalate polymer in which a high proportion of isophthalic acid is copolymerized is also prepared in advance. Alternatively, a master batch method or the like in which these are mixed with polyethylene terephthalate so that the copolymerization ratios thereof are in the ranges of 1 to 6 mol% and 0 to 10 mol%, respectively, can also be obtained. The copolymerization ratio of isophthalic acid having a metal sulfonate group is 1
If it is less than mol%, the contraction stress during heat treatment is weakly expressed, and the crimp expression is poor. If it exceeds 6 mol%, the melt viscosity of the polymer becomes so high that it is difficult to stably obtain a polymer having an appropriate degree of polymerization in the condensation reaction, and the crystallinity at the time of spinning becomes high, so that it tends to change with time. In this case, the drawability is lowered, and a composite fiber having a sufficient latent crimpability cannot be obtained. It is preferably 1 to 5 mol%, and more preferably 2 to 4 mol%. Further, a copolymer component other than the above may be introduced into the polymer (A) as long as the copolymer does not significantly impair shrinkability. The intrinsic viscosity of the polymer (A) is 0.45 to 0.66.
Is preferred.

As the polymer component (B) on the low shrinkage side, for example, a polyester substantially composed of polyethylene terephthalate is used. Of course, the polymer (B) may be copolymerized as long as the effect of developing the crimp of the polymer (A) is not significantly reduced. Further, the intrinsic viscosity of the polymer (B) is 0.60 to
A degree of polymerization of 0.70 is preferred.

If necessary, for example, titanium oxide, zirconium oxide, silicon oxide, alumina, other ceramics or flame retardants, antibacterial agents, deodorants, fragrances, and hydrophilizing agents such as sodium dodecylbenzenesulfonate are mixed as inorganic substances. May be. Further, other polymers may be added to the polymers (A) and (B) within a range that does not significantly impair the crimpability of the fiber.

The spinneret to be used may be a composite type spinneret having a hole shape such as a ○ type, a Δ type, a + type, an ∞ type, and a T type. However, the spinneret is not limited to these, and the composite form is also particularly limited. However, the side-by-side type is generally preferable to the eccentric core-sheath type because the crimp developing power is excellent.

The latently crimpable conjugate fiber used in the present invention is the above-mentioned (A),
Two polymer components of (B) were used in the range of 270 to 290 ° C. using the above-mentioned die, and a composite ratio (A) :( B) = 40 to 60:60 to 4
In the range of 0, it is particularly preferable to use eccentric core-sheath type or side-by-side type, preferably side-by-side type conjugate fiber as described above. The melt viscosities of the two polymer components during spinning are always (A)> (B), and the difference in viscosity during melting is 10
The range of 0 to 1000 poise is preferable for obtaining the composite spun fiber having excellent latent crimping ability. Composite ratio is 50: 5
The deviation from 0 is likely to cause a kneeing phenomenon in the die discharge part, so that the range of (A) :( B) = 45 to 55:55 to 45 is most preferable. The melt viscosity is a value at about 285 ° C.

Next, the latent crimpable conjugate fiber that constitutes the paper having sublimation, flexibility, stretchability, and elongation recovery has a spiral crimp after heat treatment, which improves the sublimation, flexibility, and stretchability of the paper of the present invention. It is important to impart, and it is important that the number of spiral crimps and the shape (curvature) of the crimps at that time are sharp. Specifically, the number of crimps is 4 by dry heat treatment at 170 ° C.
It is important to develop spiral crimps at 0/25 mm or more. If the number of crimps is less than 40/25 mm, the sublimation, flexibility and stretchability will be significantly reduced, and the paper will have a high bulk density. Also, the shrinkage factor during heat treatment has an important relationship with the texture, sublimation and stretchability of the paper, and the general processing conditions are preset temperature 160-180 ℃, final dry heat treatment temperature on paper.
When 170 ° C. is selected as a representative temperature satisfying 130 to 180 ° C. and the shrinkage percentage when the fiber is subjected to free shrink heat treatment at 170 ° C. is 20% or less, these items are sufficiently satisfied. Shrinkage rate is 20
If it exceeds 0.1%, the paper becomes hard and the crimping property, particularly crimp fastness, is lowered, and the durability is lowered.

The crimpable conjugate fiber having such latent crimping ability and heat shrinkability has an intrinsic viscosity of the high shrinkage side polymer (A) and the low shrinkage side polymer (B), and the polymer (A ) Is obtained by appropriately selecting the copolymerization ratio of isophthalic acid and isophthalic acid having a metal sulfonate group, the composite ratio of (A) and (B), and the stretching conditions and tension heat treatment conditions in the stretching step after spinning. . The stretching condition is to maximize the potential crimpability by stretching the fiber at 60-75% of the maximum stretching ratio after spinning. In this state, the tension heat treatment should be performed at 130-180 ° C. Thereby, high crystallinity can be maintained and a high latent crimping force is cultivated.

This latent crimpable polyester conjugate fiber is, after spinning and drawing, for example, 5 to 30/25 mm by using a conventionally known crimping device.
Mechanical crimp is applied and then cut to a fiber length of 3 to 30 mm to obtain raw cotton for papermaking. Here, the number of crimps is 5 / 25m
If it is less than m, the composite fiber will be deformed into a ring shape over time, and it will not be possible to achieve uniform dispersion during papermaking.Conversely, if it exceeds 30/25 mm, the entanglement of the fibers will become too much mechanically and the beater or pulper will Disaggregation is not sufficiently performed, which is not preferable.

The fineness of the latently crimpable polyester conjugate fiber is preferably 1 to 15 denier, more preferably 2 to 6 denier. If it is less than 1 denier, the spiral crimp developability is good, but the crimp developability is weak, sublimation is difficult to obtain, and the spinnability is deteriorated, so that the yarn may not be stably obtained. Further, in a region exceeding 15 denier, it becomes stiff and lacks flexibility, which is not preferable in some cases. The fiber length is required to be 3 to 30 mm, particularly 4 to 10 mm, because it can be uniformly dispersed in water for wet papermaking and the crimp developability is effective. When it is less than 3 mm, the dispersibility in water is good, but the fibers become short, which causes the generation of fluff and paper dust, and also reduces the paper strength, which is not preferable. If it exceeds 30 mm, the dispersibility of the fibers will be poor and the fibers will become flocculated, making it difficult to obtain uniform paper.

Further, when the addition rate of the latently crimpable polyester conjugate fiber of the present invention is less than 30% by weight, each fiber has crimp expression, but it is mixed with a heat-fusible binder fiber or other fiber to obtain crimp expression by heat treatment. However, a stress expression that overcomes the constraint of other added fibers cannot be obtained. Therefore, 30% by weight or more is necessary, and preferably 40% by weight or more. Further, a surface-treating oil agent may be added during the manufacturing process in order to further improve the dispersibility in water.

In the present invention, the heat-fusible binder fiber is a latent crimpable polyester conjugate fiber, and when a natural fiber, a recycled fiber, and a synthetic fiber optionally used are mixed and produced, a dryer part and a latent crimpable polyester conjugate fiber are obtained. The heat treatment has a role of effectively adhering each fiber in the step of developing crimp. That is, heat fusion may be performed in a dryer part at 90 to 130 ° C., or pseudo bonding may be performed. Further, it is preferable that the fibers are bonded to each other by heat fusion at the same time when the crimps are generated by heat treatment at 130 to 180 ° C. From these facts, it is a necessary condition that the heat fusion temperature is 200 ° C. or lower from the viewpoint of the heat fusion property and the heat treatment temperature of the latently crimpable polyester composite fiber. When the temperature is higher than 200 ° C., heat fusion causes a decrease in the performance of the latently crimpable polyester conjugate fiber, which is not preferable.

The heat-fusible binder fiber is not preferable because it cannot obtain flexibility unless it is a fiber made of a thermoplastic polymer.
Preferred are polyolefin fibers such as polyethylene and polypropylene, or fibers made of polyester or polyamide having a low melting point or a low softening point by copolymerization. Naturally, a core-sheath type composite fiber covered with the polymer can also be used. In this case, as the core component, an unmodified polyester-based polymer, polypropylene-based polymer, polyamide-based polymer or the like is used.

The heat-fusible binder fiber used is preferably from 1 to 15 denier, and when it is less than 1 denier, the dispersibility in water is poor, which is not preferable, and when it exceeds 15 denier, the binder effect is reduced and the texture of the paper is deteriorated. Is not preferable. Regarding crimps, it is preferable to use uncrimped ones in order to obtain water dispersibility, but 20/25 mm or less crimps in a range that does not impair water dispersibility in order to improve sublime during heat treatment. May be given. If the number of crimps exceeds 20/25 mm, the entanglement of the threads during water dispersion is likely to occur.

The addition rate of the heat-fusible binder fiber needs to be 5% by weight or more, and preferably 10 to 40% by weight. If it is less than 5% by weight, it exhibits an effect on paper strength and stretch recovery when a latent crimpable polyester conjugate fiber and natural fiber, regenerated fiber or synthetic fiber used in the present invention are mixed, and prevention of fluff appearing on the paper surface. Absent.

Next, in the present invention, other fibers may be used in combination as long as the above-mentioned fibers are used in a predetermined amount, and as the other fibers, softwood which is a natural fiber, unbleached or bleached pulp from hardwoods, and kozo , Mitsumata, bast fibers such as hemp and ramie, plant fibers from Kotton linter, bamboo and straw can also be used. Recycled pulp or waste paper may be used. These may be unbeaten pulp, or may be beaten to have a Canadian freeness of about 100 to 750 ml. The use of these natural fibers brings the advantage that the paper obtained as represented by Western paper and Japanese paper has excellent printability and is strong. Furthermore, it has the features of high affinity with water, high absorption rate, and high water absorption. It also has excellent economic efficiency. As described above, an object of the present invention is to obtain a product having a performance like a dry non-woven fabric even though it has a form and a manufacturing method like paper. The mixed pulp of cellulose pulp is obtained by high-speed papermaking and heat treatment to obtain a dry nonwoven fabric which has the texture and characteristics of paper. That is, it is one of the added fibers for exhibiting the papermaking property and the water absorption of the product.

Recycled fiber is typified by viscose rayon, but when regenerated fiber is used, it is superior to rayon paper that has been conventionally produced and is flexible due to the hydrophilicity and papermaking properties of rayon. It is possible to obtain a stretchable paper having good properties and texture.

Also, synthetic fibers such as polyester fibers, polyolefin fibers, polyamide fibers, polyacrylonitrile fibers, and polyvinyl chloride fibers impart flexibility and sublimeness to improve the texture.
Further, the polyvinyl alcohol-based synthetic fiber can be used as one for strengthening the stiffness of paper and one for enhancing hydrophilicity.

Regenerated fibers and synthetic fibers preferably have a fineness of 0.2 to 15 denier. If it is less than 0.2 denier, the dispersibility in water is poor and pills are easily formed. On the other hand, when it exceeds 15 denier, the obtained paper becomes stiff and hard, and the flexibility becomes insufficient. The number of crimps of the fiber is preferably uncrimped in consideration of dispersibility in water, but within a range not impairing dispersibility,
20 pieces / 25m to give more sublime, flexibility and elasticity
A crimp of m or less may be given. When the number of crimps is 20/25 mm or more, the dispersibility in water of the fiber is deteriorated and a ball shape is unfavorable. The fiber length is preferably 2 to 20 mm, more preferably 3 to 10
mm. If it is less than 2 mm, the dispersibility in water is good, but the fibers are short, so that fuzz or paper dust is generated. On the other hand, if it exceeds 20 mm, the dispersibility in water becomes poor, and it becomes difficult to obtain a uniform texture or texture by fluffing or stringing. The cross-sectional shape of the regenerated fiber and the synthetic fiber is not limited to a circular shape, and may be a modified shape such as a flat shape, a U-shape, a Y-shape, a T-shape, a star shape, and a triangular shape. You may have a hollow part in. The fiber form may be a fibril form. In the present invention, one kind or two or more kinds of fibers selected from the group consisting of the above natural fibers, regenerated fibers and synthetic fibers can be selected and used according to the purpose.

As described above, the fiber raw material to be used for wet papermaking has the latent crimping ability defined in the present invention, and the mechanically crimped polyester composite fiber and the heat-fusible binder fiber, and added as necessary. It is essential that the fibers are selected from the group consisting of other natural fibers, regenerated fibers and synthetic fibers.

As described above, the production method is such that 30% by weight or more of a polyester composite fiber having a latent crimping ability cut into a specific length and having a heat-fusible binder fiber is required, which is mechanically crimped. According to the above, a fiber mixture composed of one or more kinds of fibers selected from the group consisting of natural fibers such as cellulose pulp fibers, regenerated fibers such as rayon, and other synthetic fibers becomes a slurry of 1 to 10% by weight. Add water to the mixture and disaggregate with a beater or pulper to form a uniform dispersion in water. Further, a uniform dispersion of fibers in water is obtained while diluting with stirring to obtain a 0.5 to 5% by weight aqueous dispersion, and this is used as a stock solution for papermaking. If necessary, the slurry is transferred to a round or short wire of a round wire or a slanted wire through a vibrating screen or a dust removing device and divided by circulating white water to obtain a slurry concentration (pulp concentration in the slurry) of 0.02.
Make up on wire at ~ 1% by weight. Paper making may be performed in one cylinder tank or multiple tanks. Further, paper may be made with a combination of circular net and long net or short net. Excess water is removed in advance by vacuum dehydration of the wet paper sheet made on the felt, and the wet paper sheet is transferred to a dryer. The type of the dryer may be a Yankee type or a multi-cylinder type. Preferably, the wet paper web on the rotating wire mesh is dried with hot air and heated to dry and heat at once to develop crimps. In addition to this, Yankee type or multi-cylinder type,
You may use a method of drying the wet paper by adding a drying temperature of 90 to 130 ° C., winding it, and developing crimps in the heat treatment step.
Further, in the case of a continuous process, a method of passing a heat treatment process for developing crimp after the drying process may be used. The heat treatment step requires a temperature of 130 to 180 ° C. and is preferably a hot air type in which hot air penetrates the paper layer, but a heat radiation type, a heat roll, or a hot plate bonding method may be used. In order to obtain preferable sublimation and flexibility, it is preferable to avoid applying tension in the paper-making direction, the width direction and the thickness direction as much as possible, and it is usually performed under the tension sufficient for the paper to move. The crimped paper which has undergone the heat treatment step is usually passed through a hot roll of 130 to 200 ° C. at regular intervals for the purpose of smoothing its surface and fluffing. Moreover, you may give embossing for patterning and strength improvement. The sublimed paper is cooled and wound under a tension sufficient for winding.

As described above, in the present invention, since the dispersibility of fibers at the time of papermaking is extremely uniform, the obtained sublime paper is homogeneous and the latent crimping ability of the constituent fibers is at a high level.
It also has excellent sublime, with a sublimation density of less than 0.06g / cm ³ under a load of 2.5g / cm ² .

Hereinafter, specific examples of these will be described in Examples and Comparative Examples. In Examples and Comparative Examples,% is a value based on weight.

Examples 1 and 2 and Comparative Example 1 A modified polyester having ethylene terephthalate as a main component and 2.0 mol% of 5-sodium sulfoisophthalic acid copolymerized with an intrinsic viscosity of 0.55 is used as a polymer component (A).
As a polymer component (B), a polyester having an intrinsic viscosity of 0.65 consisting essentially of ethylene terephthalate units was used, and it was made into a side-by-side type with a compounding ratio of 50:50 at 285 ° C. from a round cross-section spinneret by a composite melt spinning device, 345 g It was wound at a discharge rate of / min and a speed of 1150 m / min to obtain an undrawn yarn of cable denier 2700. Draw ratio of these undrawn yarns
It was stretched 2.4 times at a stretching temperature of 75 ° C and heat-treated at a tension heat treatment temperature of 150 ° C to obtain a straight latent crimped fiber having a single fiber fineness of 2.4 denier. This fiber had a free shrinkage rate of 8% in a dry heat treatment at 170 ° C. and a crimp number of 53/25 mm.

The latent crimped fibers were mechanically crimped at a rate of 10/25 mm by an indentation crimper and cut into a length of 5 mm to prepare a raw material for papermaking (No.
1). For comparison, a material having a length of 5 mm without mechanical crimp was also used as a raw material (No. 2, Comparative Example 1).

The No. 1 and No. 2 raw materials were defibrated for 300 counts with a standard TAPPI disintegrator at a concentration of 0.2 g /, and their dispersibility was observed on paper. It was found that No. 2 had poor dispersibility because the yarn remained ring-shaped in the undispersed state. Meanwhile, No. 1
It was found that the ones were evenly dispersed.

Then, the above-mentioned No. 1 and No. 2 latent crimpable polyester composite fibers and heat-fusible binder fibers, further cellulose pulp fibers in the formulation shown in Table 1 at the same time in a TAPPI standard disintegrator 2g / Disaggregated to a concentration of 300 counts. Further 0.
Dilute to 2 g / and use the TAPPI standard square paper machine to achieve a target rice basis weight of 40
The slurry was sampled to make g / m ² and paper was made. The wet paper was dried at 70 ° C for 1 minute and then heat-treated for 4 minutes on a wire net in an air dryer at 170 ° C to obtain crimped paper.

 The heat-bonding binder fiber used was melted at 130 ° C at the sheath.
Modified polyester to wear and the core is normal polyester
Composite fiber made of fibers [Kuraray Softsoft Co., Ltd. N
-720 has a fineness of 2 denier and a fiber length of 5 mm]. Again cell
Rose pulp is an unbleached softwood pulp that has not been beaten.

As a result, in the sublime paper according to the present invention using the No. 1 fiber, the fiber exhibited a spiral crimp and was excellent in both sublimation property and flexibility. In addition, the fibers were uniformly dispersed during papermaking, and the paper had excellent texture without spots.

Examples 2 and 3 and Comparative Example 2 Intrinsic viscosity 0.4 obtained by copolymerizing terephthalic acid as a main dicarboxylic acid component as a polymer component (A) with 5 mol% of isophthalic acid and 2.5 mol% of 5-sodiumsulfoisophthalic acid.
The modified polyester of 5 was used, and as the polymer component (B), a polymer having an intrinsic viscosity of 0.60 consisting essentially of ethylene terephthalate units was used. : 50 side-by-side type, a discharge rate of 345 g / min and a speed of 1150 m / min were wound up to obtain an undrawn yarn of table denier 2700.
After converging these undrawn yarns, draw ratio 2.5 times, draw temperature 7
Stretching was carried out at 0 ° C, and heat treatment was carried out at a tension heat treatment temperature of 145 ° C to obtain straight latent crimped fibers having a single fiber fineness of 2.5 denier.

The free shrinkage of this fiber by dry heat treatment at 170 ℃ is 7.5.
%, The number of crimps was 60/25 mm.

The latent crimpable fibers were treated with 10 pieces / 25 mm in the same manner as in Example 1.
The machine crimp was applied and the fiber length was cut to 5 mm to make a papermaking raw material (No. 3).

Next, the No. 3 fiber, the heat-fusible binder fiber, and the cellulose pulp fiber were blended as shown in Table 1 in the same manner as in Example 1 to produce sublime paper. As a result, Examples 3 and 4
On the other hand, the dispersibility at the time of papermaking was excellent, and the sublime property and the flexibility were extremely excellent. Further, when the heat-fusible binder fiber was reduced (Comparative Example 2), the mechanical properties of the paper were insufficient and the texture was not satisfactory.

The measuring method of each characteristic value and the like in the present invention is as follows.

(1) Intrinsic viscosity: Measured at 30 ° C. in a mixed solution of phenol and ethane tetrachloride in equal weight.

(2) Fineness: Measured by the method of JISL-1015-7-5-1A.

(3) Number of crimps: Measured by the method of JIS L-10015-7-12-1.

(4) Free shrinkage: According to the method of JIS L-1005-7-15, treated in an atmosphere of 170 ° C for 30 minutes, 300 per denier
Measured by applying mg load.

(5) Measurement of physical properties of paper Basis weight: JISP8124 Bulk specific gravity: Four sheets of paper are superposed, a plastic plate is applied to 2.5 g / cm ^2, and the thickness is measured with a micrometer.
It was calculated from the average thickness of one sheet. As another method, there is a method of measuring thickness and bulk specific gravity by the method of JIS P8118. The measurement was carried out by this method in Examples and Comparative Examples.

Strength and fracture length: JIS P8113 Bending resistance: Cantilever method Liquid absorption: Water and mechanical oil were used as liquid substances. 10 cm ×
For the size of 10 cm, weigh the cut stock (W ₀ ). Let it soak in water and machine oil for 15 minutes and confirm that the air in the stock has been replaced. Measure the weight (W ₁ ) of the stock when the stock is pulled into the air and the drop does not drop.

It is the value obtained from the above.

(6) Hand: Judgment was made as follows.

◎ Rabbit hair-like feel (softness with slimy feel) ○ Rabbit hair-like feel (soft feel) △ Cloth-like feel (roughness) × Paper-like feel (crunchiness) Exist) (Effect of the Invention) In the production of sublimed paper, 5 to 30 mechanical crimps are applied to an eccentric core-sheath type or side-by-side type polyester composite fiber having a spiral crimp form, and the fiber length is 3 By using the one with a thickness of up to 30 mm, the dispersibility was improved and the paper-mixing property was also improved, which was unthinkable in the past. In addition, the development of spiral crimp also exhibits a synergistic effect with this mechanical crimp property, and shows a uniform texture, texture and flexibility, and a sublime paper exhibiting higher subsidence and higher paper strength is obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Okito 7471 Tamashima Otoshima, Kurashiki City, Okayama Stock Company Kuraray Co., Ltd. Examiner, Kuraray Co., Ltd. Shigemi Sawamura (56) References JP-A-1-169000 (JP, A) JP-A-61-124610 (JP, A)

Claims (1)

(57) [Claims] 1. The free shrinkage ratio in dry heat treatment at 170 ° C. is 20.
% Or less, and having a latent crimping ability of expressing three-dimensional crimps of 40 crimps / 25 mm or more after the dry heat treatment, 5 to 30 crimps / 25 m
30 eccentric core-sheath type or side-by-side type polyester composite fibers having a mechanical crimp of m and a fiber length of 3 to 30 mm
Characterized in that wet paper is made from an aqueous dispersion of a fiber mixture containing 5% by weight or more of binder fibers which are heat-fused at a weight percentage of 200% or less and heat treated at 130 to 180 ° C. Production method.